Manufacture of 1-phenyl-2,3-dimethyl-4-dimethylamino-5-pyrazolone



Patented Apr. 6, 1926. i 4 I UNITED STATES enone LOCKEMANN, or BERLIN, GERMANY.

PATENT orrlcal MANUFACTURE 9F l-PHENYL-2,3-DIME'IHYL-l-DIMETHYLAMINO-5PYRAZOLONE.

No Drawing.

To all whom it may concern:

' Be it known that I, Gnome LocunMANN, citizen of Germany, residing at Berlm, Germany, have invented a new and useful Im-.=

PI'OVGDICIltin the Manufacture of l-P henyltion. Y

2.3 Dimethyl-4: Dimethylamino--Pyrazolone, of which the following is a specifica- In orderto. produce l phenyl2.3*dimethyl 4 dimethylamino 5 pyrazolone it was hitherto necessary to make the corresponding l-amino compound by reduction of 1 compound.

phenyl-Q.3-dimethyl-4= 11itroso- 5- pyrazoloiie and to transform the free l-amino compound,'the purification of which is very tnoublesome, into the 4-dimethyl-amino Myinvention relates to a processby which the latter compound. is obtained from the -nitroso compound in one operation at a good yield; The process consists in treating the l-phenyl=2:3-diinethyll-nitroso-5-pyrazclone in presence of formaldehyde with reducing agents, for instance with a suitable metal, preferably zinc or iron, in an acid medium The final product has the following structural formula The term formaldehyde not only in-' eludes formaldehyde in the ordinary but also in the polymerized state. I

Example 1 (the parts being by weight) 22 parts of 1-phenyl-2.3-dimethyl-4-nitroso1 fi-pyrazolone are-suspended in 100 parts of a 50 percent solution of acetic acid and for 15 minutes vigorously stirred at about 4010. while 30 parts of zinc powder gradually are introduced, preferably in presence of some copper sulphate. -Then gradually 25 parts of glacial acetic acid, 80 parts of a 10 percent solution of formaldehyde and.

10 parts of zinc powder are added while the temperature is slowly increased. The stirring is continued for one hour and a quarter.

Then the mass is rendered alkaline, the 1- phenyl-2.3-dimethyl-4-dimethylamino-fipyrazolone formed is separated by means of benzene and recrystallized from ligroin or (mineral acids or organic acids);

Application filed MarehBl, 1924'. Serial No. 703,289.

the like. This reaction may 'be expressed by the following equation :0

Instead of a formaldehyde solution polymerized formaldehyde (paraformaldehyde,

trioxymethylene etc.) may also be used.

- It is even possible 'to start with the 1- pl1enyl-23-dimethyl-5'pyrazolone and to, obtain in one operation the I-Phenyl-QB-dimethyl 4- diinethylamino -5- pyrazolonc: by"

treating the starting product with'a nitrite in an acid solution and then causing reduclng agents 1n presence of formaldehyde to ,act on the l-phenyl-2.3-dimethyl--nitroso- 5-pyrazolone' formed without separating it from the reaction mixture. 1

' mample Q (the parts being by weight) 3,8 parts of l-phenyl-2.3-dimethyl-5- pyrazolonc aredissolved in 10 partsof a 40 percent sulphuric acid and .50 parts of Water. Then a solution of 1,55 parts of sodium nitrite in 15 parts of water is gradlr ally added while cooling and stirring. The

green colored. 1-phenyl-2;3 -dimethyll-nitroso-5-pyrazolone separates. Thereupon 40 parts of a' 4-0 percent solution of'sulphuric acid are added and then while cooling 6 parts of zinc powder and some copper sulphate are graduallyadded. The stirring O8ON2(C6H5) HM- 2CH20 8H: C a z o c) 2-N(CH3)2 3H O. I It is to be understood that I do not intend to be limited to the particular kind and sequence of operations nor to the proportion described in the' examples, for obvious modifications will occur to a person skilled in the art. c I I claim as my invention. v 1., The process of making l-phenyl- 2.3"-dimethyl 4-dimethylamino-5 pyraZolne ating agents to' react on 1-pheny1-2.'3-dijmethyl-a -nitroso--pyrazolone in presence of formaldehyde. "2. The

hydrogen, to, react'in an acidmedium on 1 -'pheny1 2.3 dimethyli-nitroso-5 pyrazolone in presence of formaldehyde, then renseparating the l-phenyl-2.3-dimethyli-dismethylamin'o-5-pyrazolone forr'ned;

3. The process of making 1'-phenyl 2.3-dimethyl -4- dimethy1amino-5- pyraz olone which consists in causing zinc powder in an acid medium to react on 1-phenyl-2.3-

dimethylA-nitroso-B-pyrazoloneI in pl'esen ce of formaldehyde, then rendering thesolution alkaline and separating the 'l-phenyla 2.3-dimethy1 lone formed.

4. The process of. .maling -1 phenyI-' 2.3 -dimethyl A dimethylamin'o 5 -'pyrazo- 1 lone which consists in causinghydrogen liberating agentsin presence offormaldehyde' to act on the reaction mixture resulting from the manufacture of l-phenyl fli3-dimethylipyrazolone.

ing

process of making l-phenyL' 2.3 dimethyl-4-dimethylamino15-pyrazo1one which consists in causing a metal' having the property in an acid medium of. liberating 4 dimethylamino 5 pyra zo j nitroso 5 pyrazolone from the action of niw trous .acid upon l-phenyl-2.3-dimethy l;5-

5. The process 2.3-dimethyl 4 dimethylamino 5 pyrazolone which consists in causingametal having which consists in causing hydrogen liberthe roperty in an acid medium ofliberatpyrazolone from the action ofnitrous acid upon l-phenyl-2.3-dimethyl 5-pyrazolone.

6. The process ofl making 1+pheny1.-

2.3-,dimethyl 4 dimethylamino 5 pyrazolone which consists in causingzin'c powder in v an acid medium and inp'resence of formaldedering the reaction mixture alkaline and hyde to ,adtpn the reaction mixture result- 'dimethyl gt-nitroso pyrazolone from the ydrogen, to react in an acid medium ;and in presence of formaldehyde on the reaction mixture resulting from'the manufac- .ture of 1phenyl 2.3 dimethyll-nitroso-5- of. asking '-1-phenyI- action of nitrous acid upon 1 -phenyl-- 2.3-dimethyl-5 pyrazolone.

7. In the process of reducing l-phenyl- 2.3-dimethyl-4-riitr0so-5-pyrazolone' the step which consists in-performing the reduction in presence of a catalyzer and With the addition of formaldehyde. 1

'withfthe additionof formaldehyde. In testimony yvhereof I have hereunto set 8.'-In' the process ofreducing l-phenyl-QLB- dimethyl-4 nitr0sQ-5- pyrazolone] the step which consists in performing theureductionin presence of some copper sulphate and- 

